1. Field of the Invention
The present invention relates to an angle measuring device, an optical signal switching system, and an information recording/replaying system.
2. Description of Related Art
It has been known that, in a conventional angle measuring device, a light is emitted onto a reflecting plane for a measurement which is disposed on a part of a test sample from a predetermined position and a position of a reflected light is measured so as to measure an angle of the test sample with reference to a predetermined position.
For example, in pages 2 to 3, FIGS. 1, 2 of Japanese Unexamined Patent Application, First Publication No. Hei 8-227552, an optical measuring device is disclosed which is provided with a measuring section which has four-divided light receiving planes for measuring an inclination between a disk (disk information recording medium) and an optical head to which information is recorded and measuring a thickness of a disk protecting layer. The four-divided measuring section emits a light to a disk from an optical element and receives a reflected light. The four-divided measuring section outputs an electric signal which corresponds to an amount of the received light on the light receiving planes respectively so as to measure a central position of the reflected light which is disposed in a center of a four-divided light receiving plane according to a proportional relation of the electric signals. In addition, the four-divided measuring section measures an inclination of the disk according to a shift amount of the disk in a radial direction and a thickness of the disk protecting layer according to a shift amount of the disk in a tangential direction.
Also, in pages 3 to 4, FIGS. 6 and 9 in a Japanese Unexamined Patent Application, First Publication No. Hei 11-144274, a deviation angle measuring device is disclosed in which an angle measurement light is incident onto a back plane of a galvanic mirror, a reflected light therefrom is separated into two light fluxes by a light flux separating section which is provided with a separating plane of which reflecting ratio changes according to the incident angle. Amount of light fluxes are measured independently by the light measuring devices; thus a deviated angle on the galvanic mirror is measured. Thus, a measuring accuracy can be improved by using a measurement output A which increases in accordance with a decrease of the incident angle onto the separating plane and a measurement output B which decreases in accordance with a decrease of the incident angle so as to calculate a difference “A−B”.
Also, for a system on which such an angle measuring device is carried which is used for controlling a deviated angle of an light deviating element, for example, an optical signal switching system, or an information recording/replaying system using a laser which are used for an optical communication are known.